1. Field of the Invention
The present invention relates to a tube connecting structure of an endoscope, specifically to one with a structure in which a fluid supply tube arranged through an insertion part of an endoscope is connected to a gas supply tube and a liquid supply tube via a tube joint.
2. Description of the Related Art
The distal end of the insertion part of an endoscope is provided with an observation window, through which a subject is observed, and a nozzle for jetting a gas or liquid for cleaning the observation window. A fluid supply tube for supplying the gas or liquid is connected to the nozzle. The fluid supply tube is divided at the inside of the insertion part of the endoscope into a gas supply tube for supplying gas and a liquid supply tube for supplying liquid, and the gas supply tube and the liquid supply tube are connected to a fluid supply valve, which is arranged at a hand control part of the endoscope. The gas or liquid is supplied to the liquid or gas supply tube by operating the fluid supply valve, then is jetted from the nozzle.
Japanese Patent Application Publication No. 11-253393 discloses an endoscope shown in FIG. 6, in which the fluid supply tube 5 is connected to the gas supply tube 3 and the liquid supply tube 4 through the tube joint. The tube joint is constituted of a main tube 1 and a branch tube 2, which is connected to the main tube 1, and an end 2A of the branch tube 2 is arranged adjacently to an end 1A of the main tube 1. The gas supply tube 3 is coupled with the outside of the end 2A of the branch tube 2, the liquid supply tube 4 is coupled with the outside of the end 1A of the main tube 1, and the fluid supply tube 5 is coupled with the outside of an end 1B of the main tube 1. This endoscope achieves narrowing the insertion pat by arranging the tube joint in a swollen part in between the insertion part and the hand control part in order to dispose only the fluid supply tube in the insertion part.
However, the endoscope disclosed in Japanese Patent Application Publication No. 11-253393 has a long fluid supply tube and a considerable amount of liquid or gas is left in the fluid supply tube; and hence, a gas supply operation and liquid supply operation have been difficult to switch quickly.
Moreover, the conventional tube connecting structure requires a large space d between the end 2A of the branch tube 2 and the end 1A of the main tube 1 in order to prevent the gas supply tube 3 and the liquid supply tube 4 from coming into contact with each other; and hence, the connecting part of the tubes with the tube joint must be thick. Because the connecting part of the tubes is thicker than the other parts of the endoscope, contents in the insertion part of the endoscope may become jammed, whereby they may be damaged. For that reason, narrowing the insertion part of the endoscope has been difficult to achieve.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a tube connecting structure of an endoscope with which an insertion part can be narrowed and at the same time the gas and liquid supplies can be switched quickly
In order to achieve the above-described objects, the present invention is directed to a tube connecting structure which is arranged at an insertion part of an endoscope, comprising: a tube joint which has, at a first side, a first end to which a fluid supply tube is connected, and has, at a second side, a second end to which a gas supply tube is connected and a third end to which a liquid supply tube is connected, wherein a position at which the gas supply tube is connected to the second end and a position at which the liquid supply tube is connected to the third end are differ in a longitudinal direction of the tube joint.
According to the present invention, since a position at which the gas supply tube is connected to the tube end and a position at which the liquid supply tube is connected to the tube end are located at different positions in a longitudinal direction of the tube joint, the connecting part of the gas supply tube and the connecting part of the liquid supply tube do not interfere with each other. Thus, the space between the ends of the two tubes can be narrowed which causes the tube connecting part to be narrowed; as a result, the tools inside the insertion part are not jammed. Therefore, durability of the tools improves and at the same time the insertion part is further narrowed.